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View Full Version : Do all trouble codes light up CEL?


GetMeMyStogie
04-23-2012, 08:15 AM
Or, in other words, can there be a code in the computer when the ceck engine light is off?
thathotrodlincn
04-23-2012, 08:35 AM
As far as I know, there are some codes that do not cause the CEL to light. I cannot tell you which ones.
fastblackmerc
04-23-2012, 08:48 AM
Or, in other words, can there be a code in the computer when the ceck engine light is off?

No they don't all cause the check engine light to come on.
EMAS
04-23-2012, 10:04 AM
As mentioned already not all codes will turn on the light. Non-emission related codes for example. Some codes also can stay in a pending state for awhile, the so called 2 trip codes. They must meet the "fail" conditions twice on separate cycles before they become "hard" codes and turn on the light. I used to have a list of the OBDI Ford codes and whether they would turn on the light and if they do turn on the light whether it required a single occurrence to turn on the light. Something somewhere probably exists for the OBDII codes.
RF Overlord
04-23-2012, 02:50 PM
can there be a code in the computer when the ceck engine light is off?As the others said, yes...they're called "pending" codes. My code reader will read them...not sure about the ones used by FLAPS.

Why? Do you think you have an issue?
GetMeMyStogie
04-23-2012, 06:55 PM
As the others said, yes...they're called "pending" codes. My code reader will read them...not sure about the ones used by FLAPS.

Why? Do you think you have an issue?

I had/have a bad COP, and no time to replace it. So, since I was driving around with excessive bucking anyway, I figured I'd unplug the fuel injector for the affected cylinder and spare my catalytic converters. Well, driving around like that, with one fuel injector unplugged and/or one bad cop the CEL never came on. Not even after several restarts or several dozen freeway kilometers.

I suppose it's not really necessary, since the vehicle bucking was more than enough to notify me that something was amiss under the hood.

With no CEL, I didn't know if there was any point to check for codes. Apparently, there is.
HorneDogg
04-24-2012, 01:32 AM
That seems like the same problem i am currently having now. I am going to check my MM for codes also. Thanks this was informational.